@Jeston_Furqueron, can you post the link to the C++ SDK that you are using? I’m assuming that you didn’t get this from the THETA developers section of the developer site. It’s likely managed by a different development team. I just want to make sure we’re looking at the same SDK.
@Hugues, are you looking at NVIDIA Jetson as a possible platform for your FOX SEWER ROVER? I recently saw a demo of 4K live streaming using Jetson and a THETA. The demo should be able to both stream to the Jetson board and save to storage on Jetson simultaneously. The developer wrote a usermode Linux driver to get it working. The Jetson board could serve a similar function to what you have running on the Raspberry Pi using MotionJPEG and three.js
The Jetson boards have 4K H.264 hardware decoding and encoding.
The Raspberry Pi 4 encoding with H.264 is limited to 2K.